Initial implementation of Cronet Async API.

components/cronet/android/java/src/org/chromium/net/UrlRequest.java

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.net;
 
 /**
  * HTTP request (GET, PUT or POST).
  * Note:  All methods must be called on the Executor passed in during creation.
  */
 public interface UrlRequest {
+    public static final int REQUEST_PRIORITY_IDLE = 0;
+
+    public static final int REQUEST_PRIORITY_LOWEST = 1;
+
+    public static final int REQUEST_PRIORITY_LOW = 2;
+
+    public static final int REQUEST_PRIORITY_MEDIUM = 3;
+
+    public static final int REQUEST_PRIORITY_HIGHEST = 4;
+
     /**
      * More setters go here.  They may only be called before start (Maybe
      * also allow during redirects).  Could optionally instead use arguments
      * to URLRequestFactory when creating the request.
      */
 
     /**
-     * Sets the HTTP method verb to use for this request.
+     * Sets the HTTP method verb to use for this request. Must be done before
+     * request has started.
      *
      * <p>The default when this method is not called is "GET" if the request has
      * no body or "POST" if it does.
      *
      * @param method "GET", "HEAD", "DELETE", "POST" or "PUT".
      */
     public void setHttpMethod(String method);
 
     /**
      * Adds a request header. Must be done before request has started.
      *
      * @param header Header name
      * @param value Header value
      */
     public void addHeader(String header, String value);
 
     /**
-     * Starts the request, all callbacks go to listener.
-     * @param listener
+     * Starts the request, all callbacks go to listener. May only be called
+     * once. May not be called if cancel has been called on the request.
      */
-    public void start(UrlRequestListener listener);
+    public void start();
 
     /**
-     * Can be called at any time.
+     * Cancels the request.
+     *
+     * Can be called at any time.  If the Executor passed to UrlRequest on
+     * construction runs tasks on a single thread, and cancel is called on that
+     * thread, no listener methods will be invoked after cancel is called.
+     * Otherwise, at most one listener method may be made after cancel has
+     * completed.
      */
     public void cancel();
 
     /**
-     *
      * @return True if the request has been cancelled by the embedder.
-     * TBD(mmenke): False in all other cases (Including errors).
+     * False in all other cases (Including errors).
      */
     public boolean isCanceled();
 
     /**
      * Can be called at any time, but the request may continue behind the
      * scenes, depending on when it's called.  None of the listener's methods
      * will be called while paused, until and unless the request is resumed.
      * (Note:  This allows us to have more than one ByteBuffer in flight,
      * if we want, as well as allow pausing at any point).
      *
@@ skipping 13 matching lines @@
      */
     public void resume();
 
     /**
      * Note:  There are deliberately no accessors for the results of the request
      * here.  Having none removes any ambiguity over when they are populated,
      * particularly in the redirect case.
      */
 }